Freedom Partners, a group affiliated with the Koch Brothers, has purchased at least $2.8 million in airtime in North Carolina to boost the GOP's bid to pick up the state's Senate seat, two sources told CQ Roll Call.

The airtime will benefit state Speaker Thom Tillis, who faces Sen. Kay Hagan, D-N.C., in a competitive race that could determine which party holds the Senate next year. The ad buy is for Aug. 6 through Sept. 2. The group has bought airtime on broadcast and cable in Charlotte and Raleigh, and on cable in Greenville-New Bern and Wilmington, according to a GOP source. A Democratic source also spotted additional broadcast buys in Greenville-New Bern, Wilmington, and Greensboro, plus cable time in Greensboro, bringing the total reservation to $3.4 million. Freedom Partners also made sizable ad buys for later this year in the Oregon, New Hampshire, and Louisiana Senate races in the past week.

Tillis' fundraising was lackluster in the most recent fundraising quarter, bringing in $1.6 million — less than half of Hagan's $3.6 million haul. The advertisements are issue ads, according to purchase notices posted on the Sunlight Foundation's Political Ad Sleuth. The Hagan campaign announced Tuesday that it had purchased $4.4 million in airtime for the final four weeks before election day on Nov. 4. The race is rated Tilts Democrat by the Rothenberg Political Report/Roll Call.